The present invention relates to a powder grain processing technique used for manufacturing medicines, foods, agricultural chemicals, resins, fertilizers, and the like, and particularly to a technique effectively applicable to a dry granulation apparatus in which powder grains are compacted and formed to manufacture a product.
As methods for granulating powder grains to manufacture medicines and foods, there are a wet granulation method using wet materials such as water, alcohol or the like, and a dry granulation method in which dried powder grains are compacted and formed by a pair of compression rollers. The dry granulation method obtains stable granules without necessitating wet material and have advantages of shortening of processing time and increasing efficiency of production in order to omit an intermediate step used the wet granulation method. In recent years, frequency in use of the dry granulation method is promoted.
In this dry granulation method, both of the compression rollers receive such a force from supplied powder grains that pushes and opens between the rollers, as a reaction to a compressing force generated during compacting and forming. Therefore, in conventional cases, one of the compression rollers is provided with a hydraulic mechanism to press the other compression roller and, thereby, the other roller is prevented escaping from the one. A dry granulation apparatus of this kind is described, for example, in Japanese Patent Application Laid-Open No. 49-125281 and No. 50-56373. FIGS. 14(a) to 14(c) and 15 are explanatory views showing structures thereof.
Firstly, in the dry granulation apparatus shown in FIG. 14(a), a powder grain container hopper 101 is provided at an upside thereof to temporarily store powder grains 109 that are materials and are transported with air. A feeder 102 that have screw wings for transporting the powder grains 109 supplied from the hopper 101 in a lateral direction is installed at a lower portion of the container hopper 101. Compression rollers 104 for pressing, with a high pressure, the powder grains 109 fed by the feeder 102 to compress them at a high density are provided below the feeder 102. In this case, a press cylinder 105 is attached to one of the compression rollers 104. Further, the one roller 104 is pressed against other roller 104, so that the other roller 104 is prevented escaping from the one roller 104 during the compacting and forming.
A needle-shearing device 106 for shearing a compacted object that is fed from the rollers 104 is provided below the rollers 104. Provided below the shearing device 106 is a cutter-shearing device 107 for further shearing granulation sheared by the shearing device 106 to obtain granulation of appropriate shape. A grain refiner 108 for refining the sheared granulation is provided further below the device 107. Note that these devices are always disassembled into component parts for every lot of products or the like at every appropriate period in order to prevent contamination therein. The parts and process rooms are individually cleaned. In this manner, even with respect to medicinal supplies that should avoid mixture of foreign ingredients, an operation of granulation or the like can be achieved while the devices are consistently kept clean.
Meanwhile, even if the one roller 104 are pressed so as to prevent the other roller escaping from the one roller during the compacting, then powder grains for granulation escape from both end surfaces of the rollers 104. This results in insufficient compression force and causes a drawback that solid tablets having uniform quality cannot be obtained. To prevent this escape of the powder grains, the granulation apparatus shown in FIG. 14(a) is provided with seal plates 111 and 111 as shown in FIG. 14(b), in a positional relationship as shown in FIG. 14(c). In this case, a pressure-resistant device 113 that is operated by oil pressure or the like is provided on a back part of one of the seal plates 111. Also, by the pressure-resistant device 113, the seal plates 111 and 111 are pressed so as not to come apart from end surfaces of the rollers 104. Accordingly, the powder grains supplied between the rollers 104 and 104 are compacted and formed without escaping and flowing from therebetween.
And, the granulation apparatus shown in FIG. 15(a) is also provided with similar seal plates 125 and 125. In the granulation apparatus shown in FIG. 15(a), powder grains are supplied from a powder grain container hopper 121 through a screw feeder 122 to a pair of compression rollers 123 and 123. To prevent the supplied powder grains from escaping between the rollers 123 and 123 during the compacting and forming, seal plates 125 are provided on both end surface sides of the rollers. A hydraulic cylinder 124 is also provided at one of the rollers 123 as described above.
Next, with respect to supply of powder grains to the compression rollers, a screw feeder is used to supply powder grains in many cases as described above. A screw feeder is frequently used in apparatuses, which must feed powder grains, such as a powder packaging apparatus, a powder scale apparatus, and the like, including a granulation apparatus. In this case, there are, in particularly, no problems caused by supply efficiency of the screw feeders in powder grains having a small apparent specific volume. However, there is a drawback that the supply efficiency decreases as the apparent specific volume increases. For example, in a process of performing the compacting and forming by means of compression rollers, the compacting and forming is carried out without problems in case of powder grains having a small apparent specific volume (2.5 and less). On the other hand, if the apparent specific volume is slightly larger (4 to 5), the supply efficiency of the screw feeders decreases. This results in making bad a thrust of the powder grains between the compression rollers, decreasing capacity for compacting and forming the powder grains, and reducing production efficiency. Additionally, if the powder grains have a much larger apparent specific volume (5 and more), the thrust of the powder grains is made worse and, thereby, it is no longer possible to compact and form the powder grains.
Therefore, if the powder grains have a large apparent specific volume, then it is necessary to compress the powder grains twice by the rollers or to compress the powder grains after the powder grains are pre-compressed by another compression device and the apparent specific volume thereof is reduced. That is, this processing has some wasteful steps. Although various methods and apparatuses using a tapered screw, a wave-form roll, a large-diameter roller, or the like have been proposed, any of them cannot be a satisfactory solution. On the other hand, tries for reduction of the apparent specific volume of powder grains have been made. For example, in a fine powder granulation apparatus described in Japanese Patent Application Laid-Open No. 64-44300, a structure is proposed in which fine powder containing much air is subjected to degassing during transportation thereof.
In the apparatus according to the Japanese Patent Application Laid-Open No. 64-44300, as shown in FIG. 16, a filter cylinder 132 is provided inside a trough 131, and screw wings 133 are provided in this filter cylinder 132. In this case, a ring-like chamber 134 is formed between the trough 131 and the filter cylinder 132. In addition, the ring-like chamber 134 is connected to a vacuum pump not shown through a communication tube 135. In this apparatus, the fine powder 137 supplied to a hopper 136 is degassed by the vacuum pump while being fed to the compression rollers 138 by the screw wings 133. Accordingly, the fine powder 137 comes to have the small apparent specific volume and is supplied between the compression rollers 138.
Meanwhile, various control methods about a powder grain processing apparatus have been proposed to be able to obtain compacted objects having uniform thickness and hardness without depending on operator""s intuition about thickness and hardness. FIG. 17 is an explanatory view showing a structure of a powder compression apparatus according to Japanese Patent Application Laid-Open No. 51-98682, which is an example of the above-mentioned proposition. In a dry granulating apparatus shown in FIG. 17, there are provided a supply hopper 141, a screw 143 rotated by a motor 142, and compression rollers 144 and 145. Powder grains supplied from the hopper 141 are compacted and formed between the rollers 144 and 145. In this respect, this apparatus is similar to a conventional one.
In this apparatus, however, at the rollers 144 and 145 are provided a thickness detection device 146 for detecting distance between the rollers, and a powder grain supply amount control device 147. The powder grain supply amount control device 147 controls rotation speed of the motor 142 in correspondence with a detected thickness and adjusts the powder grain supply amount from the hopper 141. In this case, a device in which a spring supports rotation shafts of the rollers 144 and 145 and which the distance between the rollers is detected on the basis of a pressure caused by the spring or a device in which the distance between the rollers 144 and 145 is detected with using a differential transformer is used as the thickness detection device 146.
However, the conventional powder grain processing apparatus as described above involves the following problems. At first, in the conventional powder grain processing apparatus, the compression rollers must be pressed by a hydraulic cylinder to increase the compacting and forming effect when compacting the powder grains. And, in order to increase the compacting and forming effect for compressing the powder grains with the rollers, seal plates must be pressed by the hydraulic cylinder. In addition, an actuator for pressing the seal plates or compression rollers, and equipment thereof are required, so that the mechanism of the apparatus is complicated and number of parts thereof is increased. This is a factor causing cost-up. Also, since powder grains attach to the actuator and equipment, contamination of the actuator and equipment may give damage to functions of the apparatus. Hence, it is desired to simplify the mechanism thereof.
Further, there are problems not preferred from view of GMP (Good Manufacturing Practice: manufacturing rules for medicines) for following reasons: products may be polluted by (hydraulic) leakage of fluid from a hydraulic cylinder, a pressure-resistance device, or the like; and abrasion powders that is abraded from the seal plates due to contact between the seal plates and the compression rollers may be mixed in the products. In this case, to prevent the abrasion powders from being generated, a hard seal material requires being used on contact portions between the seal plates and the compression rollers. These result in problems that the price of the seal plates increases and, thereby, the cost for manufacturing the apparatus raises.
In addition, in the conventional apparatus, the hopper, compression rollers and the like are individually detached from the apparatus and then are individually disassembled and cleaned. And, the process rooms are manually cleaned after putting out the apparatus. Therefore, since time and labor are required at cleaning, it is desired to improve the cleaning. In particular, cleaning must be carried out for every one of products that are subjected to batch processing, so that operation of the cleaning is very troublesome and complicated. And, since the cleaning operation tends to be done roughly, severe attention and management are required to achieve the cleaning in compliance with the GMP.
Meanwhile, in the device which detects behaviors of compression rollers to control the powder grain supply amount and to stabilize quality of compression moldings, the behaviors of the compression rollers are detected by a mechanical transmission structure using a spring or the like. Therefore, there is a problem that since dislocation from the reference position is caused due to the physical characteristics of the spring itself, such as hysteresis, settling (permanent set in fatigue), or the like, an accurate detection value cannot be obtained. Also in a device using a differential transformer, an accurate detection value can be no longer obtained due to abrasion of slidable contact points and change of voltage thereof at a transformer. This results in not achieving preferred control.
A first object of the present invention is to provide a powder grain processing apparatus capable of obtaining compression moldings made of powder grains and having uniform thickness and hardness.
A second object of the present invention is to provide a powder grain processing apparatus which has a simple structure without necessitating an actuator pressing the seal plates against the compression rollers and which prevents contamination due to oil leakage or the like and abrasion powders from the seal plates, from being mixed therein.
A third object of the present invention is to provide a powder grain processing apparatus in which a housing of the apparatus is sectioned into a process room and a drive room so that the outside of respective component parts such as a hopper, compression rollers, and the like and the inside of the process room can be automatically cleaned.
A fourth object of the present invention is to provide a powder grain processing apparatus capable of adjusting the compression condition of powder grains that are raw material, without making a complicated operation of exchanging screws.
A fifth object of the present invention is to provide a powder grain processing apparatus capable of controlling hardness of compression moldings by recognizing condition of the compression moldings as numerical values on manufacturing lines thereof.
The above-described and other objects and novel features of the present invention will be apparently understood from description of the present specification and the drawings appended hitherto.
Representative aspects of the present invention disclosed in the present application will be briefly summarized as follows.
An apparatus for processing powder grains according to the present invention, having a pair of compression rollers arranged in parallel with each other and supplying powder grains to a powder grain introduction/compression part formed between the compression rollers, thereby forming compressing moldings of the powder grains, includes a seal members being provided to face side surfaces of the compression rollers with clearance maintained from the compression rollers, and forms closer layers of the powder grains between the seal members and side surfaces of the compression rollers when the powder grains enter into the clearance, thereby sealing the powder grain introduction/compression part.
Another apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and supplying powder grains between the compression rollers, thereby forming compression moldings of the powder grains, comprises; a pressure detection means for detecting a pressure which the powder grains receive when the powder grains are pressed between the compression rollers; and a control means for adjusting hardness of the powder grains fed from the compression rollers in accordance with the pressure detected by the detection means.
Still another apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and supplying powder grains between the compression rollers, thereby forming compression moldings of the powder grains, comprises; a fine change amount detection means for detecting a fine change of a distance between the compression rollers, the fine change being caused by a pressure which the powder grains receive when the powder grains are pressed between the compression rollers; and a control means for adjusting hardness of the powder grains fed from the compression rollers in accordance with a fine change amount of the distance between the compression rollers, the fine change amount being detected by the fine change amount detection means.
In an apparatus for processing powder grains according to the present invention, the control means may adjust a pressure applied to the powder grains.
An apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and supplying powder grains between the compression rollers, thereby forming compressing moldings of the powder grains, comprises; a pair of compression roller support shafts for supporting the compression rollers; a compression roller support part for holding the compression roller support shafts; a distortion detection means attached to the compression roller support part and measuring distortion caused at the compression roller support part by a pressure which the compression rollers receive when the powder grains are pressed between the compression rollers; and a control means for adjusting the pressure applied to the powder grains in accordance with a distortion value caused at the compression roller support part, the distortion value being obtained by the distortion detection means.
In an apparatus for processing powder grains according to the present invention, the powder grain processing apparatus further comprises a powder grain press/feed means for feeding the powder grains to the compression rollers, and the control means may control the powder grain press/feed means, thereby adjusting a feed amount of the powder grains. And, the control means may control a rotation speed of the compression roller.
An apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and supplying powder grains between the compression rollers, thereby forming compression moldings thereof, comprises; a pitcher hopper provided in a front stage of the compression rollers and storing the powder grains supplied to the compression rollers; and a powder grain press/feed means connected to the pitcher hopper, arranged between the pitcher hopper and the compression rollers, and pressing and feeding the powder grains to the compression rollers, wherein the powder grain press/feed means has a transport tube internally including a screw member for pressing and feeding the powder grains.
In an apparatus for processing powder grains according to the present invention, the transport tube may comprise a deaerating barrel and a deaerating jacket, the deaerating barrel containing the screw member and being made of a member which allows air to pass and does not allow the powder grains to pass, and the deaerating jacket covering the deaerating barrel and being provided with a deaerating vent at a part thereof.
In an apparatus for processing powder grains according to the present invention, the deaerating barrel may be made of porous metal material. And, the hopper may be provided to be movable relatively along the screw member. Moreover, the hopper and the transport tube may be provided to be movable relatively along the screw member. In addition, the screw member may be provided to be able to change a distance between the screw member and the compression rollers.
An apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and supplying powder grains between the compression rollers, thereby forming compression moldings of the powder grains, comprises; a powder grain processing room sealing hermetically and containing the compression rollers in a watertight condition; and a cleaning means provided in the powder grain processing room and injecting a cleaning liquid into the powder grain processing room.
In an apparatus for processing powder grains according to the present invention, the cleaning means may be provided at least one of an upper part and side parts of the powder grain processing room.
An apparatus for processing powder grains according to the present invention, having a pair of compression rollers parallel with each other and a powder grain press/feed means for supplying powder grains to the compression rollers, and supplying the powder grains between the compression rollers with use of the powder grain press/feed means, thereby forming compression moldings of the powder grains, comprises; a shearing means provided in a rear stage of the compression rollers and shearing the compression moldings formed by the compression rollers; and a load detection means for detecting a load applied to the shearing means.
In an apparatus for processing powder grains according to the present invention, the apparatus may further comprise a control means for controlling at least one of the powder grain press/feed means and the compression rollers in accordance with data detected by the load detection means. And, the load detection means may detect rotation torque of the shearing means.
Further, the powder grain processing apparatus may be a roller compactor by dry granulating apparatus.
A method for processing powder grains according to the present invention, having a step of supplying powder grains between a pair of compression rollers arranged in parallel with each other, with use of a powder grain press/feed means provided in a front stage of the compression rollers, thereby forming compression moldings of the powder grains, comprises; a step of detecting a load applied to a shearing means during shearing the compression moldings formed by the compression rollers by means of the shearing means provided in a rear stage of the compression rollers; and a step of controlling at least one of the powder grain press/feed means and the compression rollers in accordance with the load detected.
In a method for processing powder grains according to the present invention, the load may be rotation torque for driving the shearing means.